1. Field of the Invention
This invention relates to templates and more particularly to a reusable template to be used as a guide in conjunction with an oxygen cutting torch.
2. Description of the Prior Art
The problem of accurately cutting intricate designs and patterns out of steel plate, pipe, tubing, bar stock, etc. in a minimum amount of time has plagued the welding and pipe fitting industry for years. A considerable amount of time is always spent laying out the design or cut lines prior to the actual cutting process. With respect to pipes, due to the fact that pipes have curved surfaces, it becomes an even more difficult and time consuming task to mark and cut the respective surfaces of the feeder and header pipes so that they will fit together in an accurate flush connection with their respective surfaces with respect to the angle desired between the two pipes. Naturally, as the angle changes between the header and feeder pipes, the configuration of the respective surfaces to be cut also changes.
The most widely used method of accurately joining two pipes together is to first draw on each respective pipe the area that needs to be cut out for any particular angular configuration between the respective pipes. The defacto standard procedure currently used is more fully discussed in "The Pipe Fitter's and Pipe Welders Handbook" written by Thomas W. Franklin and published by the Bruce Publishing Company. The layout equipment usually includes a square, a level, a wrap around, a strip of paper, and a piece of soap stone or chalk. Referring to FIG. 1, the usual layout procedure for constructing a T-branch is illustrated by way of example. To layout the header, one places a wrap around on the pipe at the center of the branch. A straight line is drawn around the pipe with soap stone or chalk, using the wrap around as a guide. Next, the center line is divided into four equal parts by a procedure well known in the art. A straight line, about ten inches long, is then drawn on the pipe at each quarter mark. These lines are then numbered as shown in the figure, with line number 3 on top, number 4 on the bottom and numbers 1 and 2 on the sides. Marks A and B, as shown in the figure, are then marked off with soap stone on line 3 on each side of the center line. The distance from A and B to the center is equal to one half of the outside diameter of the branch. Point C will be located at the intersection of the center line and lines 1 and 2. A wrap around is then placed on the pipe and lined up with point A and point C on lines 1 and 2. These points are then connected with a chalk line. The wrap around is next lined up with points C, B, and C and connected with a chalk line. Sometimes a pointed cut at point C is not desired. For a rounded cut, one locates point D. The distance from point C to point D is equal to two times the thickness of the pipe wall. A chalk line is then drawn by free hand connecting point D with the lines from A and B. The cut is made along these lines with the cutting tip at all times directed to the center of the pipe. Then, the edges are beveled to a forty five degree angle after the cut has been made.
Referring again to FIG. 1, the procedure for laying out the branch pipe for cutting is illustrated. Again, the surface of the branch pipe is divided into four equal parts by a procedure well known in the art. A straight line is then drawn from the end of the pipe at the quarter marks about six inches long. These lines, as shown in FIG. 1 (C), are numbered with line number 3 on the top, number 4 on the bottom and numbers 1 and 2 on the sides. Points A and B on lines 1 and 2 are then marked off with soap stone, the distance from A and B to the end of the pipe being equal to one half of the outside diameter of the pipe, which is noted as distance E.
A wrap around is then placed on the pipe and lined up with points A and C on lines 3 and 4 at the end of the pipe. These points are then connected with a chalk line. The wrap around is then lined up with points C, B and C and a chalk line is drawn connecting these points again, for a rounded cut, point D is located. The distance from point C to point D is equal to two times the thickness of the pipe wall. A chalk line is then drawn by free hand connecting point D with the lines from A and B. The branch pipe is then cut with a cutting torch along these layout lines by using a radial cut, but the cut is not beveled.
Similar marking procedures are employed for laying out cut lines for: turns; laterals; Y connections; reducers including the concentric, eccentric, and two cut eccentric reducer; for blanking off pipe including the orange peel, and the bull plug; and the full size cross connection.
With respect to designs cut from plates, the design is usually first drawn on the plate prior to cutting. This also can be very time consuming depending on the design pattern.
Once can readily see that these layout procedures currently used for laying out cut lines is extremely time consuming and is responsible for the majority of the time used in cutting patterns and welding two pieces of pipe together at any angular configuration.
To reduce this layout time, templates or jigs have heretofore been developed. Various other schemes have also been devised for making plate, bar stock or pipe to be cut. Representative patents in the general area of this invention are U.S. Pat. Nos. 1,683,953 (Multiple Template); 1,915,924 (Notching Guide for Tubes); 2,155,705 (Adjustable Template Means); 3,128,560 (Pipe Templates and Methods of Cutting Pipe).
While the various methods and templates as discussed above, or variations of them, have been used extensively for laying out cut lines, they all have serious drawbacks. The major drawback is that the template must be placed accurately around the workpiece to be marked so that the cut line can be drawn in the right configuration. Considerable difficulty has been encountered in prior art devices especially in pipe templates due to the fact that the pipe to be marked may vary in diameter to such an extent as to seriously effect the gripping action of the template. Split templates were developed to overcome these problems, however, still considerable difficulty arises due to variations in pipe diameters and accurately drawing the correct configuration. Further, all the prior art templates must actually be placed on or around the work piece to be marked and secured in place before a cut line is drawn. The work piece still needs to be marked prior to cutting. This layout procedure still requires a considerable amount of time prior to actually cutting the work piece.
Consequently, a need exists for improvements in templates which will considerably reduce the amount of layout time.